Incorporating web designer's HTML pages into an MVC4 application

Question

We are embarking on a new project which will be using the ASP .NET MVC4 platform.

I have been informed that the design is being outsourced to a custom design firm and they will be supplying us with HTML pages and stylesheets.

How easy will it be to incorporate these css stylesheets and HTMl pages in our application? Do I need to ask for something more than HTML pages?

My personal experience is limited to one site that was built for an in-house and I used the HTMLHelper to generate Views. Another past experience I have from long-ago is using Classic ASP and that was a breeze since I could literally mash up ASP and HTML together.

My question is, what is this a good approach to incorporating HTML and stylesheets from a web designer into an ASP.NET MVC4 web application?